Doak's Confidential Guide was the one that got me started about 20 years ago.....it's Doak acting like Brian and giving EVERY golf course he ever played a grade from 1 to 10......funny stuff....from there you just start reading the books by the greats and about the greats - Mackenzie, Tillinghast, Ross, Macdonald, Thomas, Raynor, etc....Shackelford is very good by the way - try his The Golden Age of Golf Design